Chemical ecology of obligate pollination mutualisms
Obligate mutualisms between flowering plants and their seed-parasitic pollinators represent some of the most fascinating insect-plant interactions known. Four such associations, in which the female of the seed parasite actively pollinates its host, have been documented, including fig wasps on figs, yucca moths on yuccas, senita moths on the senita cactus, and Epicephala moths on Phyllanthaceae plants. These systems offer excellent models for evolutionary and ecological studies on co-evolution, species diversification, and the origin and stability of mutualisms. A key feature in these systems is the mechanism(s) facilitating the attraction of exclusive pollinators to host flowers, which is crucial for the reproduction and survival of either partner in these interactions.
My research is focused on the role of floral scent in the pollination mutualisms involving Yucca and Phyllanthaceae. In both systems, a female moth uses her mouthparts (unique tentacles in yucca moths and modified proboscis in Epicephala moths) to gather pollen from a host flower. She then seeks out another host flower, where pollen deposition and oviposition take place. Larvae of these pollinators require maturing seeds of their host, and by pollinating the flower she has oviposited into, the female moth ensures the presence of maturing seeds for her progeny. All seeds are not consumed, however, and thus both partners benefit from the interaction. In both associations, mating, oviposition and pollination occur at night, and host flowers are fragrant only at night. Thus, olfactory cues are suggested to be key sensory signals in these insect-plant interactions.
Pollination and oviposition by a female of a host-specific (but not yet formally described) Epicephalamoth on its host Glochidion acuminatum, Amami-Oshima Island, Japan, May 2006. Recorded by: Atsushi Kawakita.